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碩士論文公告區 |
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| 年度： | 90 | |
| 姓名： | 石秉根(Ping-Ken Shih) | |
| 論文題目(中)： | 顆粒粒徑對飽和砂質土壤液化相關行為影響之研究 | |
| 論文題目(英)： | Influence of Grain Size on Liquefaction-related Behavior of Saturated Granular Soils | |
| 摘要(中)： | ||
| 臺灣地質構造主要受到歐亞大陸版塊與菲律賓海板塊擠壓影響，故地震活動極為頻繁。地震可能引起土壤顆粒重新排列使土壤顆粒間的孔隙趨向於緊密，此時土壤內的孔隙水壓顯著增加而土壤有效應力將減低至零，以致於土壤將失去剪力強度，土壤成為液態現象，即稱為液化，此現象在地震中被證實為造成損害之主要原因之一。本研究將以前人設計之土壤液化箱並利用小型震動台，作震動液化試驗來探討土壤顆粒粒徑大小對液化的影響及相關行為研究。 研究結果顯示在均勻單一粒徑顆粒土壤組成狀態下，最容易發生液化的顆粒粒徑大小範圍為0.1mm ~ 0.3mm，在砂土分類中屬於細砂。細顆粒砂土在中等緊密至緊密狀態下（Dr=50 ~ 70%），欲發生液化所需之震動能量約為鬆散狀態下（Dr小於50%）的4 ~ 5倍，且液化後沉陷量降低可達30%左右。若現地土壤實際相對密度Dr在50%以下（鬆散）時，則當該地區地震震度在4＋級（地動加速度140 ~ 160gal）時，高地下水位的局部性區域有可能會有液化災害產生。若現地土壤實際相對密度Dr=50 ~ 70%（中等緊密至緊密），欲發生液化現象該地區之地震震度至少要達到5-級（地動加速度200 ~ 230gal），土壤之抗液化能力與液化後沉陷量的多寡主要皆取決於細顆粒砂質土壤含量上。本文研究最後提出一套適用於飽和砂質土壤抗液化能力之評估方式，期望未來對臺灣學術及工程界能有所助益。 |
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| 摘要(英)： | ||
| Since Taiwan is located in the major Pacific seismic zone, it is noticed that earthquake occurs very frequently and is the major natural hazard in the region. One of the causes of severe damages to the structures during major earthquakes is the development of liquefaction in saturated sand deposits. When a saturated sand deposit is subjected to ground vibrations, it tends to compact and decrease in volume; if drainage is inadequate, the tendency to decrease in volume results in an increase in pore water pressure. When pore water pressure built up is equal to or greater than the overburden pressure, the sand deposit becomes partially or completely liquefied. The purpose of this research was to study the effect of grain size on liquefaction-related behavior of sandy soils using portable soil tank and shaking table. For soils consist of an uniform grain size, results of the study revealed that the grain size diameters most vulnerable to liquefaction during earthquake are from 0.1 to 0.3mm. The liquefaction resistance in terms of energy of dense sand deposit (Dr=50%~70%) is 4 to 5 times greater than that of loose sand deposit (Dr<50%). In addition, the settlement resulting from liquefaction in dense sand deposit may be 30% less than that of loose sand deposit. In general, for saturated sand deposits within a depth of 6m (20ft), the earthquake intensity required for liquefaction in loose conditions (Dr<50%) may be as high as level 4+ in Taiwan earthquake intensity scale (equivalent to ground acceleration of 140~160gal), while it may be as high as level 5- (equivalent to ground acceleration of 200~ 230gal) in dense conditions (Dr=50%~70%). Results of the study also indicate that both the liquefaction potential and the resulting settlement strongly depend on the content of find sand particles (0.1~0.3mm) in the sand deposits. In the last, the results of the study provides a preliminary method for estimating liquefaction potential and resulting settlement of sand deposit during earthquake. This method includes parameters of (1) grain size content in percent, and (2) energy / volume strain and individual weighting of each grain size determined from laboratory results of the study. |
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| 檔案： | 沒有相關檔案 | |
| 相關連結： | http://ethesys.lib.cyut.edu.tw/ETD-db/ETD-search-c/view_etd?URN=etd-0718102-175515 | |